/*
 * Copyright 2015 The Netty Project
 *
 * The Netty Project licenses this file to you under the Apache License,
 * version 2.0 (the "License"); you may not use this file except in compliance
 * with the License. You may obtain a copy of the License at:
 *
 *   http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
 * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
 * License for the specific language governing permissions and limitations
 * under the License.
 */
package io.netty.resolver;

import io.netty.util.concurrent.EventExecutor;
import io.netty.util.concurrent.Future;
import io.netty.util.concurrent.FutureListener;
import io.netty.util.concurrent.Promise;
import io.netty.util.internal.UnstableApi;
import java.net.InetAddress;
import java.net.InetSocketAddress;
import java.util.ArrayList;
import java.util.List;

/**
 * A {@link AbstractAddressResolver} that resolves {@link InetSocketAddress}.
 */
@UnstableApi
public class InetSocketAddressResolver extends AbstractAddressResolver<InetSocketAddress> {

  final NameResolver<InetAddress> nameResolver;

  /**
   * @param executor the {@link EventExecutor} which is used to notify the listeners of the {@link
   * Future} returned by {@link #resolve(java.net.SocketAddress)}
   * @param nameResolver the {@link NameResolver} used for name resolution
   */
  public InetSocketAddressResolver(EventExecutor executor, NameResolver<InetAddress> nameResolver) {
    super(executor, InetSocketAddress.class);
    this.nameResolver = nameResolver;
  }

  @Override
  protected boolean doIsResolved(InetSocketAddress address) {
    return !address.isUnresolved();
  }

  @Override
  protected void doResolve(final InetSocketAddress unresolvedAddress,
      final Promise<InetSocketAddress> promise)
      throws Exception {
    // Note that InetSocketAddress.getHostName() will never incur a reverse lookup here,
    // because an unresolved address always has a host name.
    nameResolver.resolve(unresolvedAddress.getHostName())
        .addListener(new FutureListener<InetAddress>() {
          @Override
          public void operationComplete(Future<InetAddress> future) throws Exception {
            if (future.isSuccess()) {
              promise
                  .setSuccess(new InetSocketAddress(future.getNow(), unresolvedAddress.getPort()));
            } else {
              promise.setFailure(future.cause());
            }
          }
        });
  }

  @Override
  protected void doResolveAll(final InetSocketAddress unresolvedAddress,
      final Promise<List<InetSocketAddress>> promise) throws Exception {
    // Note that InetSocketAddress.getHostName() will never incur a reverse lookup here,
    // because an unresolved address always has a host name.
    nameResolver.resolveAll(unresolvedAddress.getHostName())
        .addListener(new FutureListener<List<InetAddress>>() {
          @Override
          public void operationComplete(Future<List<InetAddress>> future) throws Exception {
            if (future.isSuccess()) {
              List<InetAddress> inetAddresses = future.getNow();
              List<InetSocketAddress> socketAddresses =
                  new ArrayList<InetSocketAddress>(inetAddresses.size());
              for (InetAddress inetAddress : inetAddresses) {
                socketAddresses
                    .add(new InetSocketAddress(inetAddress, unresolvedAddress.getPort()));
              }
              promise.setSuccess(socketAddresses);
            } else {
              promise.setFailure(future.cause());
            }
          }
        });
  }

  @Override
  public void close() {
    nameResolver.close();
  }
}
